1. Field of the Invention
This invention relates in general to the construction of electrodes and in particular to a gas diffusion electrode for electrochemical cells with acid electrolytes which comprises a hydrophobic layer of gas permeable electrically conductive material and a hydrophilic layer containing a catalyst closely bonded to the hydrophilic layer.
2. Description of the Prior Art
The invention relates particularly to a gas diffusion electrode for electrochemical cells with acid electrolytes, preferably a cathode for air-operation. In electrochemical cells with acid electrolytes, air can be used as a cheap oxidant, without the necessity for an elaborate purification of the air, as it is necessary in alkaline cells. The corresponding air electrodes (cathodes) can be designed as gas diffusion electrodes.
In the operation of these electrodes under air (20% oxygen) with normal climate-related humidity, there is a considerable voltage drop, compared to the operation with pure oxygen. The resulting power drop can not be sufficiently reduced by artificial liquidification of the air supplied to the electrodes. Besides, this requires an additional engineering effort. Furthermore, the cell voltage builds up to a stationary value in load variations with a relatively large time constant.